Maintenance & Technical > KX500 Original

Dry piston install

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gwcrim:
Stewart, oh STEWART!?!?!?!?

BDI:
I wonder what the temp of the rings spikes up to when you fire the engine dry. It could go real high and hurt the temper of the rings making them soft but if it got cooled off fast by oil and fuel they could become even harder then they were.

KXcam22:
I've been doing some thinking and I doubt you would find me doing a dry install.  Firstly, piston acceleration can be upwards of 100,000 ft/sec.sq at which speed I am sure the rings will be cleaning themselves of any surface oil instantly, therefore the lubed bore would be protecting the piston from galling (a good thing) but not preventing the rings from getting full, almost unlubed contact to seat.  Also in a 2-stroke the rings bulge into the ports a tiny bit each stroke.  In a new engine, the cylinder lube would be benefitial in helping the rings slowly wear the correct path without gouging or chattering at the port chamfers.  Just some ideas. Cam.

PS. the one idea that did show up was to never use regular oil as a cylinder lube.  Always use 2-cycle oil.  Non 2-cycle oil doesn't burn properly and leaves carburization (sticky carbon) in the ring grooves which can lead to poor long-term ring perfomance.

CR480R:

--- Quote from: BDI on March 03, 2009, 01:44:44 PM ---So then would you put a small block chevy 350 together this way too??...

--- End quote ---

I have once.. The total seal brand rings I used specified using a dry-film lubricant that they sell... It was dry powder like substance, very similar to graphite.. It had no issues with ring seal and is still going strong for its 3rd owner.. I cant say I would recommend it for someone else, but it worked fine for me..  The general concensus is that using oil is the way.. But some engine builders swear by dry assembly and it seems to work for them.. I have put 5 or 6 different 2-strokes together dry or with a light coat of WD-40... right or wrong no issues occured.. I think the roundness and finish of the bore are more important than anything else along with giving the engine ample time to wear in before subjecting the engine to heavy loads or high engine speeds... Idk.. just my thoughts, interesting topic for sure

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